Pile driving mandrel construction and method for driving extensible piles



I H. DE R. GIBBONS Fume E967 FILE DRIVING MANDREL CONSTRUCTION AND33232483 METHOD FOR DRIVING EXTENSIBLE PILES Filed Oct. 2, 1964 2Sheets-Sheet l I N VE TOR. Hurry ole R. Mwltwns ATTGIRNEYS June 27, 1967H. DE R. GIBBONS 3,327,483

FILE DRIVING MANDREL CONSTRUCTION AND METHOD FOR DRIVING EXTENSIBLEFILES Filed Oct. 2, 1964 "2 Sheets-Sheet INVENTOR. Hayrry ale R; abbbons9 W, W 8 Jam ATTORNEYS United States Patent PILE DRIVING MANDRELCONSTRUCTION AND METHQD FOR DRIVING EXTENSIBLE PHLES Harry de R.Gibbons, North (Ianton, @hio, assignor to The Union Metal ManufacturingCompany, Canton,

Ohio, a corporation of Ohio Filed Oct. 2, 1964, Ser. No. 400,996 7Claims. (Cl. 6153.7)

The invention relates to piles, and more particularly to the driving andforming of piles in which a tapered tubular metal shell is driven intothe ground with a tapered, substantially rigid, driving mandrel or core,and the tapered shell being driven is used to pull sheet metal shellextension sections into the ground above and connected to the taperedshell, and in which the mandrel then is extracted from the shellsections and the latter are filled with suitable bearing material,preferably concrete, to form the pile; and the present inventionconstitutes improvements on the invention set forth in the copendingGibbons and Rausch application S.N. 398,291, filed Sept. 22, 1964,entitled, Pile Driving Mandrel Construction and Method.

The copending application illustrates, describes and claims a mandrelconstruction which solves many problems and eliminates many difiicultiesheretofore encountered in the art. Such mandrel construction includes asubstantially rigid, longitudinally continuous mandrel member having ahead and a tapered shell-contacting portion, ring means surrounding theupper end of the mandrel spaced below the head and engageable with theupper end of a tapered tubular pile shell being driven when the taperedmandrel portion is telescoped within such shell, and a driving capreleasably telescoped over and engaged with the mandrel head and spacedfrom the ring means initially driving the mandrel to penetrate the shellwith the cap thereafter engaging the ring means for simultaneouslydriving the heads of the mandrel and shell.

A tapered shell of one length, top diameter and taper normally will bedriven by a tapered mandrel of one particular or standard size, as shownin said copending application. Ordinarily, a large number of pile shellsmay be driven at a particular driving site for the foundations of abridge, building, and the like. When conditions are ideal, substantiallyall pile shells driven at the same site may have approximately the samedriven length. Thus all pile shells supplied for a given job normallywill have the same length and will be driven by the one standard mandrelfor such shells. If some of the shells when driven are too long, the topends of the shells when formed of metal may be cut oil? with a torch,and no real problem is presented.

Situations arise, however, where the pile shells being driven areshorter than required, or where the known length of the required pile isconsiderably longer than standard tapered pile shells immediatelyavailable, or where special tapered mandrels required for longer taperedshells are not immediately available, or where extremely long piles arerequired which involve a plurality of metal shell sections that must bejoined together end to end either before or during driving.

In such situations, a standard length tapered shell may serve adequatelyas a bottom portion of a driven shell, provided that such shell can beextended upwardly with additional shell sections of sufiicient length toprovide the final required pile shell length.

Prior arrangements for driving a pile shell deeper than the initiallydriven shell section and which is extended by additional shell sectionshave involved driving the initial sect-ion with a mandrel that did nottouch the sides of the section, then extracting the mandrel, and theninsert- 3 ,327,483 Patented June 27, 1967 ing a heavy walled shellextension section which was top driven to the required depth. Thisprocedure is undesirable in requiring the expense of an extensionsection left in the ground having a heavy enough wall to stand up underthe blows of the pile driving hammer.

Other arrangements have involved the use of a heavy walled drivingextension to sink the initial nose section deeply in the ground, afterwhich a thin walled shell extension section of corrugated culvert-likeform is dropped within the heavy walled driving extension member toprovide the shell extension for the nose section, and then the heavywalled driving extension member is'pulled out of the ground for reuse.This arrangement while using a thin walled shell extension section alsohas dis-advantages involved with the pulling of the heavy walled drivingmember, with ground cave-ins related to the pulling operation, and withthe non-uniformity of ground contact with the thin walled shell afterthe heavy walled member is pulled.

Accordingly, it is a general object of the present invention to providea mandrel and pile shell construction with which a tapered shell sectioncan be driven into the ground utilizing the improved mandrelconstruction and method of said copending application, and with whichthe driven tapered section can be extended upwardly by additional thingauge metal extending sections pulled into the ground by the taperedsection as the tapered section continues to be driven deeper and deeperinto the ground for the desired or required distance.

Furthermore, it is an object of the present invention to provide animproved means and procedure for driving extensible piles.

In addition, it is an object of the present invention to provide a newmandrel construction and driving procedure by which an extensible pileshell may be driven into the ground comprising a tapered preferablyfluted lower shell section having a shoulder at its upper end to whichextending sections are connected and pulled into the ground by thetapered section as the latter is driven, in which the extending sectionsmay be formed of light gauge material that cannot withstand theapplication of direct driving forces, and in which the extendingsections may have any shape, thickness or diameter and normally will notbe tapered.

Furthermore, it is an object of the present invention to provide a newmandrel and pile shell construction and driving procedure with whichlight gauge pile shells of various lengths involving light gaugeextension sections that cannot withstand direct driving blows may bedriven into the ground using only one special mandrel and one size oftapered pile shell section, thereby substantially reducing theinvestment in driving equipment necessary for driving pile shellsregardless of the penetrated depth and reducing the cost of the drivenpiles by eliminating the necessity of using heavy walled shell sections,while at the same time assuring proper bearing contact between the shellsections and the ground into which the shell sections are driven.

Finally, it is an object of the present invention to pro vide a new piledriving mandrel construction and procedure for driving extensible thinwalled tubular pile shells, eliminating difficulties heretoforeencountered in the art; eliminating complicated and costly mandrel andshell structures; achieving the indicated objects in a combined, simple,effective and inexpensive manner; and solving problems and satisfyingneeds existingin the art.

These and other objects and advantages apparent to those skilled in theart from the following description and claims, may be obtained, thestated results achieved, and the described dificulties overcome, by theapparatus, combinations, parts, elements, subcombinations, arrangements,relationships, constructions and methods which comprise the presentinvention, the nature of which are set forth in the following generalstatements, a preferred embodiment of whichillustrative of the best modein which applicant has contemplated applying the principles-is set forthin the following description and shown in the drawings, and which areparticularly and distinctly pointed out and set forth in the appendedclaims forming part hereof.

The nature of the improved apparatus for setting piles of the presentinvention may be stated in general terms as including a tapered tubular,preferably longitudinally fluted, ribbed or corrugated sheet metal pileshell section having a nose and an upper end; connection ring meansconnected to the upper end of said tapered shell section formed withshoulder means; a thin gauge tubular sheet metal pile shell extensionsection connected to said connection ring means and extending upwardlytherefrom; a substantially rigid longitudinally continuous main mandrelmember having a head portion with an upper end and a taperedshell-contacting portion, the tapered mandrel portion being shorter thanthe tapered shell section and being tapered selectively on the same orslightly greater taper than that of the tapered shell section; asupplemental or secondary heavy-walled tubular, preferably cylindrical,mandrel member telescoped over and surrounding the head portion of themain mandrel member and being located within the thin gauge shellextension section having a lower end resting on the connection ringshoulder means and having an upper end located adjacent the upper end ofthe main mandrel head portion; mandrel and shell-engaging and drivingcap means releasably telescoped over and engaged with the upper end ofthe main mandrel head portion, the tapered mandrel portion whentelescoped within the tapered shell section before driving with the capmeans engaged with the main mandrel head having the cap means spacedabove the upper end of the secondary mandrel; means for establishingdriving engagement between the cap means and the upper end of thesecondary mandrel after the tapered mandrel portion has been driven intothe tapered shell section to penetrate said shell section apredetermined distance; the tapered mandrel portion frictionallywedge-engaging and slightly radially expanding the tapered shellsectionduring the predetermined penetration of the shell section by the taperedmandrel portion; the cap means when driving engagement is establishedwith the upper end of the secondary mandrel member, also top driving thetapered shell section through said connection ring shoulder means intothe ground by blows applied to said cap means; and said frictionallyengaged and top-driven tapered shell section pulling said shellextension section into the ground until the shell sections are driven tothe desired depth.

The nature of the improved method of driving into the ground extensiblepile shells composed of thin-walled tapered and thin-walled tubularshell extension sections in accordance with the invention may be statedin general terms as including the steps of telescoping a downwardlyinwardly tapered portion of a substantially rigid longitudinallycontinuous mandrel having a head at one end and a nose at the other endinto a tapered tubular sheet metal pile shell section also having ashoulder at one end; a nose at the other end and a thin gauge tubularpile extension section extending upwardly from the shoulder; thendriving the mandrel relatively into the tapered shell section topenetrate said shell section and frictionally wedge-engage taperedtelescoped contacting surfaces of said mandrel and tapered shell sectionto establish frictional driving contact therebetween; controlling thepenetration of the tapered mandrel portion in the tapered shell sectionto a predetermined amount; then after such predetermined penetrationsimultaneously driving the tapered shell section head and mandrel headto drive the tapered shell section into the ground to the Al desireddepth; and pulling the thin gauge tubular shell extension section intothe ground by the driving of the tapered shell section.

By way of example, an embodiment of the improved mandrel constructionand extensible pile shell driving procedure is shown in the accompanyingdrawings forming part hereof in which:

FIGURE 1 is a side elevation with parts broken away and in sectionillustrating the improved construction with the shell sections to bedriven telescoped over the mandrel components at the beginning of adriving operation;

FIG. 2 is a side view of the parts shown in FIG. 1 i1- lustrating themandrel and shell components during driving after a predeterminedpenetration of the tapered FIG. 5 is an enlarged sectional view taken onthe line 55, FIG. 1;

FIG. 6 is a plan View with parts in section of the parts shown in FIGS.1 and 3; and

FIG. 7 is a section looking in the direction of the arrows 7-7, FIG. 4.

Similar numerals refer to similar parts throughout the various figuresof the drawings.

A tapered tubular pile shell is indicated generally at 1 and preferablyis formed of light gauge sheet or strip metal such as 11 gauge stripsteel. The pile shell 1 has a connection ring generally indicated at 2secured to the upper end 3 of tapered shell 1, and pile shell extensionsections generally indicated at 4 are connected to connection ring 2.

The tapered shell section 1 is adapted to be driven into the ground andto pull the extension sections 4 into the ground as the tapered section1 is driven. When the pile shell sections 1 and 4 have finally beendriven to the proper position, they may be filled with concrete to forma pile.

Shell 1 preferably is provided with a closed lower end or nose 5 andpreferably also is provided with longitudinally continuous outturnedflutes 6 which not only reinforce or stiffen shell 1 but serve otherpurposes to be described.

Shell 1 may have any desired length and because .of its taper, itreadily penetrates the ground. and may, therefore, readily be driven todesired depth. Shell 1 in accordance with the invention preferably has astandard length, as for example, 30 feet in length, and may be used topull extension sections 4 of varying lengths into the ground to serve asshells for piling required to be driven to various depths. However,since the tapered section 1 is standardized, the driving mandrel for thetapered section also may be standardized so that only one mandrelconstruction normally is required for driving extensible pile shells ofvarious lengths.

Pile shell section 1 may be driven by usual pile driving equipment, notshown, which may include a hammer and head guide 7 supported in a usualmanner on the driving equipment and a reciprocating hammer plunger 8.

A mandrel generally indicated at 9 may be used for driving the taperedshell section 1 and the extension section 4 into the ground, the lowerportion 10 of mandrel 9 being tapered downwardly inwardly and beingextended upwardly by preferably cylindrical mandrel portion 11 whichforms the head portion of the mandrel terminating at an upper end 12.Head portion 11 and upper end 12 of mandrel 9 preferably may beconstructed like the mandrel shown in said copending application toinclude an annular recess 13 on which a floating driving ring 14 ismounted for movement axially of the mandrel head portion 11 and up anddown recess 13.

The upper end 12 of mandrel head portion 11 preferably is taperedslightly upwardly inwardly at 15 and may be closed by a welded-in headcap 16. Upper head end 12 also preferably is provided with an extractorbar 17 extending through member 11 and having laterally projecting ends18 preferably formed with openings 19, the extractor bar 17 beinglocated below head cap 16 and above recess 13 and floating drive ring 14which surrounds recess 13.

A mandrel and shell engaging and driving cap generally indicated at 20forms one of the components of the mandrel construction. The cap 20preferably includes an upwardly extending cup-shaped sleeve 21 taperedat its upper end as indicated at 22. Cap 20 may be l-ashed to hammerguide 7 by cables 23 which extend through openings 24 formed in ears 25projecting from cap 20 in the region of the cap member partition wall26. A knockout plate 27, a cushion member 28, and an anvil 29 preferablyare contained in the usual manner within the recess formed by cap sleeve21 so that the blows of a hammer 8 are imparted to cap 20 throughmembers 29, 28, and 27.

Driving cap 20 also is formed with a downwardly opening cup-shapedsleeve 30 having an annular lower end surface 31. Sleeve 30 is adaptedto be telescoped over and engaged with the upper end 12 of mandrel headportion 11, the cavity formed by sleeve 30 preferably conforming incontour to the contour of the upper end 12 of mandrel head portion 11.

Sleeve 30 is formed with downwardly opening cutouts 32 which straddlesthe lateral projecting extractor bar ends 1 8 when sleeve 30 istelescoped over mandrel head portion 11 with the cap partition wall 26engaged on the top end 12 of the mandrel as shown in FIGS. 1 and 2.

Cap member 20 when telescoped over and in driving engagement with topend 12 of head portion of mandrel 9, as shown in FIG. 1, has the endsurface 31 of sleeve 30 spaced above floating ring 14 when the latter isat or adjacent its lower limit of floating movement along recess 13, asgenerally indicated in FIG. 1. When mandrel 9 is assembled with pileshell sections 1 and 4 to be driven, a secondary mandrel sleeve 33 isassembled therewith telescoped over and surrounding mandrel head portion11 and engaged at its lower end 34 with connection ring 2 and adapted tobe engaged at its upper end 35 by floating ring 14. Secondary mandrelsleeve 33 has a heavy rigid tubular wall which telescopically surroundsthe head portion 11 of mandrel 9and extends telescopically within thepile shell extension section 4, as shown. The upper end 35 of secondarymandrel sleeve 33 is located above the upper end of shell extensionsection 4.

' When assembling the shell sections together preparatory to driving,the connector ring preferably is welded to the upper end 3 of taperedshell section 1 but may be secured thereto by any other suitable means.Connector ring 2 (FIG. 4) preferably has a ledge or shoulder portion,36from which sleeve portion 37 projects downwardly within and ispreferably welded to the upper end 3 of tapered shell section 4 forpermanent connection thereto. Another sleeve member 38 projects upwardfrom ledge portion '36 to which shell extension section 4 may beconnected. As shown, shell extension section 4 is preferably a lightgauge corrugated sheet metal member and may be formed of, say 18 gaugematerial generally having the shape of a corrugated culvert. Theextension section 4, however, may be corrugated, round, or fluted incross section and its thickness and diameter can vary depending on theground conditions existing at the location where the piilng is to bedriven. Furthermore, the extensi-on section 4 may have any desiredlength throughout its generally tubular extent. Also section 4 maycomprise several pieces :axially connected together to provide thedesired length. As shown, extension section 4 may be connected in anydesired manner as by welding to sleeve 38 of connection ring 2 so thatsleeve section 4 will be pulled into the ground as the tapered section 1is driven.

Several operational steps in the use of the improved construction areillustrated in FIGS. 1, 2, and 3. When a shell 1 is to be driven alongwith a connection ring 2 and extension section 4, the mandrel 9 andsupplementary mandrel sleeve 33 are telescoped into the shell sections,as shown in FIG. 1, with the lower tapered end 10 of mandrel 9 withinthe tapered shell section 9, with supplementary mandrel sleeve 33resting at its lower end 34 on connection ring ledge 36, and with theupper ends 35 and 12 of sleeve 33 and mandrel head section 11,respectively, extending above the upper end of shell extension section4. Driving cap 20 is lashed to the hammer guide 7, driving head sleeve30 is telescoped over the upper end of mandrel head portion 11, and theentire assembly is suspended above the desired driving location ready tobe driven. The parts, elements, and components at this time have therelative positions shown in FIG. 1 wherein the floating driving ring 14rests on the top end of supplementary mandrel sleeve 33 which in turnrests at its lower end 34 on ledge 36 of connection ring 2.

Driving blows from hammer 8 through cap 20 drive mandrel head portion 11engaged by cap 20 downward so that tapered portion 10 of mandrel 9relatively penetrates tapered shell portion 1. Penetrating movement ofmandrel 9 establishes frictional driving wedge-engagement between thetapered outer surface of tapered mandrel portion 10 and the ribs ofshell flutes 6 along the telescoped and engaged portions of said taperedmandrel and shell portions. This frictional wedge-engagement slightlyradially expands tapered shell 1 along its length as the tapered mandrelportion 10 penetrates tapered shell section 1. v

In accordance with the invention, the amount of axial wedge penetrationof shell 1 by mandrel 9 and the amount of radial expansion of shell 1 iscontrolled such as to prevent shell bursting. Furthermore, taperedportion 10 of mandrel 9 is shorter in length than tapered shell section1, as shown, and at no time does the lower end of the mandrel engage thenose 5 of shell 1. The controlled mandrel-shell penetration ispredetermined to be an amount not greater than the spacing between thelower end 31 of cap sleeve 30 and floating ring 14 when the parts areassembled as shown in FIG. 1 with the mandrel 9 telescoped withintapered shell section 1 but not penetration wedged.

' All'parts normally are assembled in telescoped relation as shown inFIG. 1 before driving blows are applied or wedging occurs. That is, aneffort is made to select the required length of shell extension sections4 and these are connected together and assembled as shown so that themandrel does not have to be extracted during driving to insert anadditional shell extension section. Furthermore, the showing of FIG. 1is typical since variations in tapered flute formations, wear, etc. canslightly alter the relative positions shown. With such initialpositioning, the predetermined indicated amount of penetration oftapered shell section 1 by the tapered mandrel portion 10 thatsubsequently can occur during initial driving may be measured as theaxial distance of the spacing between the top face of floating ring 14and the lower end surface 31 of cap sleeve 30.

With the parts in the position of FIG. 1, operation of hammer 8 drivesmandrel 9 downward in shell 1 to penetrate the tapered shell section-thepredetermined'or controlled amount or distance until the relativeposition of the parts shown in FIG. 2 is established. At this time capwall 26 is in driving engagement with the upper end 12 of head portion11 of mandrel 9, end surface 31 of sleeve 30 is in driving engagementwith floating ring 14 which in turn engages upper end 35 of secondarymandrel sleeve 33, the lower end 34 of which engages connection ringshoulder 36 to establish direct driving engagement from cap 20 to thehead or upper end 3 of tapered shell section 1, and the controlledpredetermined penetration of shell 1 by mandrel portion is achieved.

Under these conditions frictional driving contact between flute valleysof shell section 1 and the engaged tapered surfaces of mandrel portion10 has been established, and the force of hammer blows is transmitted bydriving cap not only to the upper end 3 of shell 1 but alsosimultaneously to shell 1 through the frictionally engaged taperedsurfaces of mandrel section 10 and shell 1.

As indicated, the tapered portion 10 of mandrel 9 may have the sametaper as that of shell 1 or the mandrel taper may be slightly greaterthan that of the shell so that during controlled penetration of theshell by the mandrel frictional wedge contact therebetween isestablished progressively from the top of tapered mandrel section 10 tothe lower end thereof.

Driving of shell 1 continues by operation of hammer 4 until shellsection 1 has reached the desired driven position in the ground. At thistime driving head 20 is raised free of driving engagement With the upperend of mandrel 9 to a position somewhat as illustrated in FIG. 3. Thenan extractor convertor ring generally indicated at 39 in FIG. 3 isinserted between end surface .31 of cap sleeve and the top surface offloating driving ring 14 to maintain cap wall 26 spaced from the upperend 12 of mandrel head portion 11.

Ring 39 preferably is composed of similar half sections 40 and 41 hingedor bolted together as indicated at 42. Extractor convertor ring 39 thusis removable and insertable when desired. After extractor ring 39 hasbeen inserted as shown in FIG. 3, an upward pull may be exerted on theends of extractor bar 17 by cables 43 suspended from a winch on thedriving equipment. Cables 43 may be connected to extractor bar 17 at alltimes to suspend the mandrel 9 from the driving equipment and the cablesare only subjected to lifting force during mandrel extracting or liftingoperations.

Hammer 8 is then operated to drive cap 20 against extractor ring 39while an upward pull through cables 43 is exerted on mandrel 9. In thismanner the frictional engagement between the tapered portion 10 ofmandrel 9 and tapered shell section 1 is loosened or disengaged andmandrel 9 may be extracted or lifted from the driven shell leaving shellsections 1 and 4 in the ground to serve as a form in which concrete maybe poured if desired to provide the final pile structure.

During extraction of mandrel 9, the supplementary mandrel sleeve 33 maybe lashed by suitable means not shown to lift it from the driven shellseither at the same time that mandrel 9 is extracted or after extractionof mandrel 9.

In accordance with the invention, particularly where exceedingly longpiles are required, a standardized tapered shell section 1 may be driveninto the ground through driving wedge engagement with a tapered mandrelportion telescoped therein and also simultaneously by top driving thetapered shell section, and the tapered shell section is used to pull anytype of shell extension section into the ground, of any shape, thicknessor diameter desired and normally not Itapered, and which may be made ofconsiderably thinner tubular shell material than can withstand directdriving.

Thus, any job normally only will require one standard size of tapereddriven pile section and a matching man drel to be supplied, regardlessof the depth of penetration. Light gauge shell extension sections asrequired to meet depth conditions for any particular pile are pulleddown by the driven standard tapered shell section.

This is all accomplished in accordance with the present invention bysecuring a shouldered ring at the top of a tapered shell section and bydriving the tapered section with a main and a secondary mandrel.

Accordingly, the present invention provides an improved pile drivingmandrel and shell construction and procedure which are simple andpractical to use and relatively low in cost as compared with the priordriving of extensible piles; which solve problems that have existed inthe art; which avoid difliculties previously encountered in the drivingof extensible piles; which enable light gauge tapered sheet metal pilesections to be driven and extremely light gauge shell extension sectionsto be pulled into the ground; and which eliminate other difiicultiesheretofore encountered in the art, achieve the stated objects,accomplish the many new functions and results described, and generallysolve problems which have existed in the art.

In the foregoing description, certain terms have been used for brevity,clearness and understanding but no unnecessary limitations are to beimplied therefrom beyond the requirements of the prior art, because suchterms are used for descriptive purposes and are intended to be broadlyconstrued.

Thus, the terms rigid or substantially rigid used herein are intended todescribe mandrels having sufficient rigidity and strength to be driveninto the ground or removed therefrom Without failure under normalcondition; and the terms ribbed, corrugated, or fluted are used hereinmore or less synonymously to refer to tapered structures with whichspaced line contacts may be established in telescoped relation to and inengaged relation with other tapered members circular in cross section.

Moreover, the description .and illustration of the invention is by wayof example and the scope of the invention is not limited to the exactstructural details shown or to the lengths and metal thickness describedfor example, because the sizes of the various parts and components maybe varied to provide other structural embodiments without departing fromthe fundamental principles of the invention.

Having now described the features, discoveries and.

ments, subcombinations, arrangements, relationships, con-- structions,methods, and steps and mechanical equivalents obvious to those skilledin the art are set forth in the appended claims.

I claim:

1. Apparatus for setting piles, including a tapered tubular sheet metalpile shell section having a nose and an upper end provided with an outerside, a thin gauge tubular sheet metal shell extension section having alower end provided with an inner side, ring means connected to thetapered section upper end and to the extension section lower end withthe extension section extending upwardly of the upper end of saidtapered section, said ring means including a portion extending inwardlyof the inner side of the extension section to the outer side of theupper end of the tapered section and forming a driving shoulder, asubstantially rigid longitudinally continuous main mandrel member havinga head portion with an upper end and a tapered shell contacting portionextending downwardly from the head portion and telescoped in contactwithin the tapered shell section, a secondary tubular mandrel membertelescoped within said shell extension section and surrounding the mainmandrel head portion having a lower end engaged with said drivingshoulder and having an upper end located adjacent but spaced below themain mandrel upper end, mandrel-engaging and shelldriving cap meansreleasably telescoped over .and engaged with the main mandrel upper end,the tapered mandrel portion in cont-act with the tapered shell sectionprior to driving holding the cap means spaced from driving engagementwith the upper end of said secondary mandrel member, and means forestablishing driving engagement between the cap means and the upper endof the secondary mandrel member to directly drive the upper end of thetapered shell section through said secondary mandrel and drivingshoulder after the mandrel has been driven into the tapered shellsection to penetrate the tapered shell section a predetermined distance.

2. The apparatus defined in claim 1, in which the means for establishingdriving engagement between the cap means and the upper end of thesecondary mandrel member includes a floating driving ring movableaxially of the main mandrel head portion and located between the capmeans and the upper end of the secondary mandrel member.

3. The apparatus defined in claim 1, in which the tapered shell sectionis longitudinally fl'uted and the tapered mandrel portion is circular incross section.

4-. The apparatus defined in claim 1, in which the shell extensionsection is corrugated and generally cylindrical in extent.

5. The apparatus defined in claim 1, in which the ring means comprisesan annular shoulder portion, a downwardly extending sleeve portionconnected with the upper end of the tapered shell section, and anupwardly extending sleeve portion surrounding the annular shoulderportion and connected with the lower end of the shell extension section.

6. The apparatus defined in claim 1, in which the tapered mandrelportion is shorter in length than the tapered shell section, and inwhich the cap means engaging the upper end of the mandrel establishesdriving engagement with the upper end of the secondary mandrel memberand through the latter with the ring means and the upper end of thetapered shell section before the lower end of the mandrel contacts thetapered shell section nose on penetration by the mandrel of the taperedshell section.

7. The method of driving extensible piles including the steps oftelescoping a downwardly inwardly tapered portion of a substantiallyrigid longitudinally continuous mandrel having a head at one end and anose at the other end into a light gauge tapered tubular sheet metalpile shell section having a shoulder at one end, a nose at the other endand a lighter gauge tubular sheet metal pile extension section extendingupwardly from the shoulder; then driving the head of the mandrel todrive the mandrel relatively into the tapered shell section to penetratethe shell section a predetermined distance and frictionally wedge-engagetapered telescoped contacting surfaces of the mandrel and tapered shellsections thereby establishing frictional driving engagementtherebetween; then simultaneously driving the mandrel head and thetapered shell section shoulder to drive the tapered shell section intothe ground to the desired depth; pulling the shell extension sectioninto the ground by the driving of the tapered shell section; thenfreeing the mandrel of driving engagement while maintaining drivingengagement with the tapered shell section shoulder; and then driving theshell section shoulder while pulling on the mandrel to extract themandrel from the driven shell sections.

References Cited UNITED STATES PATENTS 4/1935 Thornley 6153.7 4/1936 Orret a1. 6 1--53.7

1. APPARATUS FOR SETTING PILES, INCLUDING A TAPERED TUBULAR SHEET METALPILE SHELL SECTION HAVING A NOSE AND AN UPPER END PROVIDED WITH AN OUTERSIDE, A THIN GAUGE TUBULAR SHEET METAL SHELL EXTENSION SECTION HAVING ALOWER END PROVIDED WITH AN INNER SIDE, RING MEANS CONNECTED TO THETAPERED SECTION UPPER END AND TO THE EXTENSION SECTION LOWER END WITHTHE EXTENSION SECTION, SAID RING MEANS OF THE UPPER END OF SAID TAPEREDSECTION, SAID RING MEANS INCLUDING A PORTION EXTENDING INWARDLY OF THEINNER SIDE OF THE EXTENSION SECTION TO THE OUTER SIDE OF THE UPPER ENDOF THE TAPERED SECTION AND FORMING A DRIVING SHOULDER, A SUBSTANTIALLYRIGID LONGITUDINALLY CONTINUOUS MAIN MANDREL MEMBER HAVING A HEADPORTION WITH AN UPPER END AND A TAPERED SHELL CONTACTING PORTIONEXTENDING DOWNWARDLY FROM THE HEAD PORTION AND TELSESCOPED IN CONTACTWITHIN THE TAPERED SHELL SECTION, A SECONDARY TUBULAR MANDREL MEMBERTELESCOPED WITHIN SAID SHELL EXTENSION SECTION AND SURROUNDING THE MAINMANDREL HEAD PORTION HAVING A LOWER END ENGAGED WITH SAID DRIVINGSHOULDER AND HAVING AN UPPER END LOCATED ADJACENT BUT SPACED BELOW THEMAIN MANDREL UPPER END, MANDREL-ENGAGING AND SHELLDRIVING CAP MEANSRELEASABLY TELESCOPED OVER AND ENGAGED WITH THE MAIN MANDREL UPPER END,THE TAPERED MANDREL PORTION IN CONTACT WITH THE TAPERED SHELL SECTIONPRIOR TO DRIVING HOLDING THE CAP MEANS SPACED FROM DRIVING ENGAGEMENTWITH THE UPPER END OF SAID SECONDARY MANDREL MEMBER, AND MEANS FORESTABLISHING DRIVING ENGAGEMENT BETWEEN THE CAP MEANS AND THE UPPER ENDOF THE SECONDARY MANDREL MEMBER TO DIRECTLY DRIVE THE UPPER END OF THETAPERED SHELL SECTION THROUGH SAID SECONDARY MANDREL AND DRIVINGSHOULDER AFTER THE MANDREL HAS BEEN DRIVEN INTO THE TAPERED SHELLSECTION TO PENETRATE THE TAPERED SHELL SECTION A PREDETERMINED DISTANCE.